In a short range communication system, a machine-to-machine (hereinafter abbreviated M2M) communication is generally defined as a peer-to-peer communication. In this communication system, communication entities perform a mutual communication in accordance with a mutually defined and agreed random access protocol. And, it is not necessary to consider whether one of the entities is actually connected to a public internet network. On the other hand, a communication on a cellular network should be defined as a communication between a base station and a user equipment or a communication between an entity equivalent to a base station and a user equipment, and all communication behaviors are controlled by a base station or an entity equivalent to the base station.
In this protocol, a cellular network restricts operations of all user equipments by a predetermined rule, thereby obtaining maximum throughput. On the contrary, this rule has an over-ruled aspect depending on an application or a channel environment of a user equipment. For instance, a base station makes a decision of a power consumed for a user equipment to transmit the same data traffic. As all behaviors of the user equipment in transmitting the same data traffic are controlled or regulated by a base station, a short range communication should operate in a manner that the base station is situated in-between. Thus, in order for a user equipment to perform a short range communication with low power consumption, the user equipment should have a structure of utilizing another radio resource access technology (RAT) or has no choice but to accept the inconvenience of a cellular network.
Due to such a structural problem, as a channel environment of a user equipment is vulnerable, when the user equipment accesses a network, the user equipment accesses the network by searching for a new access path with restriction put on using an optimal communication path. This problem restricts the following advantages. In particular, if a user equipment has a good channel state with a neighbor user equipment despite being located in a shadow area, the user equipment communicates with the neighbor user equipment and the neighbor user equipment having a good channel communicates with a base station. Therefore, power efficiency and throughput of the user equipment, which becomes a source of data traffics, can be enhanced.
For another instance, if a user equipment intends to communicate with a neighbor user equipment by utilizing RAT of a cellular network instead of using an RAT different from that of the cellular network, the corresponding data exchange is controlled by a base station. Yet, in this communication structure, the corresponding data should be forwarded to a base station and is then retransmitted to a target user equipment no matter how much the user equipments are located physically closer to each other. Hence, this structure may turn out to be an unreasonable communication structure.
According to this application, when user equipments (e.g., M2M (machine to machine) devices) are present and managed, it is able to consider a model in which a specific device plays a role as an aggregator while a server (e.g., M2M server) accesses each of the user equipments via a base station. According to another application, in case that an owner supposed to manage user equipments manages the corresponding user equipments in a manner of being adjacent to them, it is preferable that data is directly delivered to the managed user equipment of the owner rather than delivered to a base station. In doing so, compared to a case of using a different RAT (e.g., WiFi, Bluetooth, Zigbee, etc.), this case can configure an inexpensive ecosystem because a user equipment needs not to include a modem for multiple RATs. Moreover, since the multiple RATs are not used, it may be unnecessary to implement a processing configuration for unnecessary application layers.
Moreover, in designing a radio interface (air-interface) for an M2M communication or a UE-to-BS (user equipment to base station) communication based on a single RAT, it is able to overcome the inefficiency in designing the radio interface based on multiple RATs independently. In particular, if a short range communication and a cellular network access are allowed by utilizing a single RAT, it is able to configure a very efficient ecosystem of user equipments.
The above-mentioned features are applicable to HTC (human type communication) devices as well as to M2M devices or user equipments. In this case, both a short range communication and a long range communication can be performed via a user equipment with small power and low complexity. And, an active QoS management is enabled to achieve an efficient power consumption level and an efficient throughput management.
In this situation, however, a detailed method of supporting a transmit power configuration for a mobile relaying or an M2M communication except a BS-to-UE communication in a cellular network based communication system has not been proposed yet. If the transmit power configuration for the BS-to-UE communication is used as it is, since it is unable to configure a power optimized for an M2M link, it may become inefficient. Therefore, the demand for a method of maximizing the advantages of the M2M communication using the efficient M2M power configuration is rising.